1. Field of the Invention
This invention relates to a check valve apparatus, and particularly to standing check valve for use in oil wells.
2. Description of the Prior Art
The world's energy demands have placed an increasing emphasis on maximizing the amount of oil pumped from each producing well. Obviously, the volume of oil to be pumped from a well is first limited by the interior diameter of the well casing or other conduit. A secondary limitation on the maximum fluid flow from the casing is the necessity of incorporating protective apparatus in the casing, such as a standing check valve which is normally disposed in the bottom portion of the casing beneath the pumping apparatus to permit the pumping apparatus to be removed or shut off without losing the column of oil previously pumped and existing in the casing. A ball valve has been preferred for such check valving apparatus inasmuch as it is extremely reliable and is not apt to hang up in the opening position or fail to achieve a proper seal in its closed position. However, the conventional ball valve does provide a substantial impairment to fluid flow in its open position and there is a need therefore for a check valving apparatus having the reliability of a ball valve, but yet providing substantially increased fluid flow area in the open position of the valve apparatus.